Drug & supplement interaction

Strophanthus + Quinidine

Quinidine brand names: Quinaglute Duratabs, Quinaglute, Duraquin, Cardioquin, Cin-Quin, and others.

Major Interaction
Medically reviewed by · Updated September 2026
The bottom line Major

Strophanthus has a major interaction with Quinidine. Contraindicated; cardiac medications, including quinidine, may increase the risk of cardiac glycoside toxicity; .

Read the full interaction report
SeverityMajor
LikelihoodProbable
EvidenceD
What do Severity, Likelihood & Evidence mean?
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Interaction report

Strophanthus and Quinidine

Here is the interaction we found between these two, with the evidence behind it.

Major

QUINIDINE

Contraindicated; cardiac medications, including quinidine, may increase the risk of cardiac glycoside toxicity; .
Severity Major Likelihood Probable Evidence D

Interaction has not been documented in well-controlled studies, however, the interaction has been demonstrated in some small human studies or in controlled animal studies in conjunction with multiple case reports..

Dr. Brian Staiger, PharmD, BCPS
Dr. Brian Staiger explains PharmD, Clinical Pharmacist

Here's the short version: this is a combination I'd steer you away from. Strophanthus contains cardiac glycosides (ouabain), which act a lot like digoxin and directly affect your heart's rhythm. Quinidine is well known to raise blood levels of cardiac glycosides by interfering with how the body moves and clears them, so the two together can stack up to dangerous amounts.

When glycoside levels climb too high, you can see nausea, vision changes (like seeing halos), confusion, and serious, even life-threatening, heart rhythm problems. Since quinidine itself is a powerful antiarrhythmic with a narrow safety margin, the risk is real even though this concern is based mostly on how these drugs work. Please don't combine them on your own. Talk with your doctor or pharmacist first.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Gruenwald J, Brendler T, Jaenicke C. PDR for Herbal Medicines. 1st ed. Montvale, NJ: Medical Economics Company, Inc., 1998.

What These Ratings Mean

Every interaction above is graded three ways — here’s the key to each label.

Severity how clinically significant the interaction is
Major

Clinically significant. Avoid the combination, or use only under close professional supervision.

Moderate

Usually worth avoiding or managing — may need monitoring, a dose change, or timing apart.

Minor

Generally not serious. Be aware of it and mention it to your pharmacist.

Likelihood how strong the evidence is that the interaction actually happens in people
  • LikelyWell-controlled human studies have demonstrated the likely existence of this interaction.
  • ProbableInteraction has not been documented in well-controlled studies, however, the interaction has been demonstrated in some small human studies or in controlled animal studies in conjunction with multiple case reports.
  • PossibleInteraction has been documented in animal or in lab research, or the interaction has been documented in humans but is limited to case reports or conflicting clinical research exists.
  • UnlikelyInteraction has been demonstrated in animal or in lab research but has been shown not to occur in humans.
Evidence the quality of the studies behind the rating (graded A–D)
  • AHigh-quality meta-analysis (quantitative systematic review).
  • BCase-control study.
  • CConsensus.
  • DAnecdotal evidence.

These ratings are for information only. Never start, stop, or otherwise change your therapy before speaking with your provider.

Keep it in perspective

Strophanthus Also Interacts With Other Medications

Strophanthus has 2 major, 120 moderate known drug interactions in our database — the Quinidine one above is one of them. If you take anything else, check it against the full list below.

Major 2 Moderate 120 No known interaction 2,708 (incl. Quinidine)
Taking anything else?

Check Another of Your Medications Against Strophanthus

Covers the 2,830 medications we’ve checked against Strophanthus. Pick one to open its full report.

From our Q&A

Questions About Strophanthus or Quinidine

These are real questions from readers, answered by the pharmacists at HelloPharmacist — written by a person, not generated from a database. Each one covers Strophanthus or Quinidine, not necessarily both, but if one is close to what you were about to ask it will usually go further than a database entry can:

Not quite your question? Ask our pharmacists directly — it is free, there is no account required, and answers usually come back within 24 hours.

Everything else you take

See Every Supplement That Interacts With Quinidine

This page covers Strophanthus only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Quinidine page lists 207 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), American Hellebore (major), Arsenic (major), Beer (major) and Cesium (major).

By severity: 15 major · 157 moderate · 35 minor.

From our pharmacist’s overview on the Quinidine page

“Grapefruit belongs nowhere near quinidine. The juice blocks the main enzyme that clears this heart rhythm medicine, so quinidine levels can climb into dangerous territory, and it leads a list of 207 supplement and herbal ingredients I would treat with real seriousness, 15 of them rated major.”

Reviewed by 2 · Jul 18, 2026

Open the Quinidine interaction page

How much people look this up

Where Strophanthus and Quinidine Sit Against Everything Else

Out of every supplement and medication people look up on HelloPharmacist, here is where these two land this week — and which way each has been moving.

Supplement Strophanthus
Top half

#523 of 1,452 supplements looked up here in the last 7 days

29 days ago today
Medication Quinidine
Top 25%

#614 of 2,830 medications looked up here in the last 7 days

29 days ago today

Position among everything looked up on this site, not a measure of how commonly either one is used or how important it is. A supplement can climb this list because of a news story. It counts every request to the page, automated ones included, and nothing here identifies anyone.

Supplement

About Strophanthus

What is Strophanthus?

  • Heart failure
  • Angina (chest pain)
  • Irregular heartbeat
  • Circulation support
  • Traditional African arrow poison (historical)

Strophanthus is a plant that contains powerful heart-affecting compounds called cardiac glycosides (the best known is ouabain/g-strophanthin). Because these substances can strongly affect heart rhythm and are toxic in the wrong amount, Strophanthus is not a casual supplement and should never be used without close medical supervision. Reliable modern evidence for its supplement use is limited.

Read the full Strophanthus monograph & all interactions
Medication

About Quinidine

What Is Quinidine Used For?

Brand names: Quinaglute Duratabs, Quinaglute, Duraquin, Cardioquin, Cin-Quin, Quinora, Lin-Qin, Quinova, Quinidex Extentabs

Quinidine is used to help restore a normal heart rhythm in people with atrial fibrillation or atrial flutter (irregular, rapid heart rhythms originating in the upper chambers). It is also used on an ongoing basis to reduce how often those episodes come back, in patients whose episodes are frequent and poorly tolerated — but only after other options have been tried first.

Quinidine sulfate oral tablets and quinidine gluconate extended-release oral tablets are both approved for these heart-rhythm uses. Quinidine sulfate tablets are additionally used as part of an approved treatment regimen for life-threatening Plasmodium falciparum malaria, in combination with quinidine gluconate injection (the central component of that regimen). Both formulations may also be used to suppress recurrent, documented life-threatening ventricular arrhythmias (dangerous rapid rhythms in the lower chambers of the heart), such as sustained ventricular tachycardia.

See full Quinidine drug information
Keep checking

Other Drugs & Strophanthus

Browse every other medication we’ve checked against Strophanthus — both the ones with a known interaction and the ones without. Select any drug for the full detail.

2Major
120Moderate
0Minor
2,707No known interaction
2 Major 120 Moderate 2,707 No interaction
Major

2 interactions

Moderate

120 interactions

Showing 60 of 120 moderate interactions — see all 120 on the Strophanthus page.

No interaction 2,707 drugs checked — show the list

We also checked Strophanthus against these medications and found no known interaction in our sources. Open any page to confirm.

Showing the 60 most looked-up of 2,707 medications checked with no known interaction — see the full Strophanthus list.

See the full Strophanthus interactions page
See every supplement checked against Quinidine, ranked by severity
Sources

Sources & How We Checked

Interaction details are evidence-graded and sourced from the Natural Medicines database. The medication overview comes from MedlinePlus.

Content is written and reviewed by licensed HelloPharmacist pharmacists. See our data sources and editorial standards for how this information is built and checked.

Parts of this content are provided by the Therapeutic Research Center, LLC.

DISCLAIMER: Currently this does not check for drug-drug interactions. This is not an all-inclusive comprehensive list of potential interactions and is for informational purposes only. Not all interactions are known or well-reported in the scientific literature, and new interactions are continually being reported. Input is needed from a qualified healthcare provider including a pharmacist before starting any therapy. Application of clinical judgment is necessary.

© 2021 Therapeutic Research Center, LLC

Keep exploring
Strophanthus monograph › Uses, safety, and every drug interaction in one place Quinidine supplement interactions › Every supplement checked against Quinidine, ranked by severity Quinidine drug information › The full plain-English guide to this medication Supplement interaction checker › Check any supplement or product against your medications Browse medications A–Z › Every drug we've checked against herbs & supplements Ask a pharmacist › Free, personal answer from our licensed team
Pharmacist Counseling Corner

Taking Strophanthus and Quinidine Together: Common Questions

Can you take Strophanthus with Quinidine?
This is rated a major interaction, so the combination is best avoided unless your doctor or pharmacist has specifically told you otherwise. Read the full details on this page and confirm with your pharmacist before combining them.
How serious is the Strophanthus and Quinidine interaction?
We rate it Major. This is a clinically significant combination that is generally best avoided, or used only under the direct supervision of your physician or pharmacist.

Written and reviewed by the HelloPharmacist editorial staff. Our editorial policy

Still Have a Question About Quinidine and Strophanthus?

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This information is for education only and is not a substitute for professional medical advice. Always check with your pharmacist or doctor before starting, stopping, or combining supplements and medications.